[Clinical significance of small, dense LDL cholesterol in patients with hyperlipidemia and type 2 diabetes].

We investigated the serum levels of small, dense LDL-cholesterol (sd LDL-C) in patients with hyperlipidemia and type 2 diabetes. An analytical assay was used to determine the levels of sd LDL-C, employing a filter method using a separating agent of polyanion and divalent cation natures. Reference intervals of sd LDL-C in normal healthy subjects (n=113) ranged from 8.0 to 42.0 mg/dl. We found a strong correlation between the levels of sd LDL-C and both the ratio of LDL-C/apolipoprotein B and the LDL migration index. The LDL migration index was analyzed using polyacrylamide gel disk electrophoresis. The levels of sd LDL-C in patients with types IIa, IIb and IV hyperlipidemia were significantly higher than those in normal subjects and in patients with normal lipidemia. The levels of sd LDL-C in patients with type IIb were higher than those with types IIa and VI. Examination of patients with polydisperse LDL showed that the levels of nodular and disrupted type sd LDL-C were higher than the levels of symmetry type sd LDL-C. Moreover, the levels of sd LDL-C in patients with type 2 diabetes were higher than those in normal subjects. A high level of sd LDL-C in patients with type 2 diabetes was found to be an indicator of possible complications of hyperlipidemia and lessly related to glycemic control. Therefore, the determination of sd LDL-C levels can be useful in the diagnosis of patients with hyperlipidemia and polydisperse LDL and in patients with type 2 diabetes with complications of hyperlipidemia and atherosclerosis.

[A simple separative method for measuring serum amyloid A in high-density-lipoprotein and low-density-lipoprotein fractions using the phosphotungstic acid-Mg2+ precipitation procedure].

We developed a simple separative method for measuring serum amyloid A (SAA) in both high-density-lipoprotein (HDL) and low-density-lipoprotein (LDL) fractions. It was devised using the SAA agglutination method and phosphotungstic acid-Mg2+ precipitation procedure for evaluating HDL-cholesterol (HDL-C). The new method is also able to detect amyloid A (AA) in each fraction with precision. The results of both the present method and the method using SAA agglutination and the dextran sulfate-Mg2+ precipitation procedure showed a strong correlation when used to measure the level of SAA in the LDL fraction of patients (r = 0.997; p < 0.0001). Reference intervals in normal healthy subjects (n=75) ranged from 0.5 to 4.7 microg/ml in the HDL fraction and from 0.1 to 1.9 microg/ml in the LDL fraction. SAA in the LDL fraction of subjects with hyperlipidemia was significantly higher than in normal subjects and subjects with normal lipidemia. SAA in the HDL fraction and total sera of subjects with hyperlipidemia was significantly higher than in normal subjects; however, it was not higher than in patients with normal lipidemia. The present methods for detecting SAA, especially in the LDL fraction, might benefit from analyzing patho-physiological events in various lipid disorders.

[Clinical significance of serum-glycated apolipoprotein B measured by the digestion LDL sediment fraction with protease].

We previously reported an assay method for serum glycated aplipoprotein B (G-apo B) using protease. The present study demonstrated correlations between serum G-apo B levels and some other serum parameters, from which a clinical significance of the G-apo B in diabetics was deduced. Serum G-apo B determined by the present method was significantly correlated with glyco-albumin and glycohemoglobin. However, no significant difference was observed between G-apo B levels and total cholesterol and the other lipid items. The mean levels of serum G-apo B in type 2 diabetics with or without hyperlipidemia were significantly higher than in normal subjects (p<0.001). In a comparison of type 2 diabetics with and without hyperlipidemia, the G-apo B levels were not significant between the former and the latter. However, those levels were significantly higher in the nodular and disrupted type of LDL than in the symmetry type of LDL. Even more, the G-apo B levels in the nodular type of LDL were significantly higher than in the disrupted type of LDL. Therefore, the G-apo B levels might be considered an independent risk marker of diabetes hyperlipidemia and atherogenesis.

A simple precipitation method for measuring sialic acid in apolipoprotein B-containing lipoproteins in plasma.

BACKGROUND: A convenient method for the measurement of sialic acid in plasma apoB-containing lipoproteins is described. METHODS: Dextran sulphate-Mg(2+) precipitation and enzymatic sialic acid assay were combined and applied to analysis of plasma from 96 healthy controls and 136 hyperlipidaemic subjects of types IIa (n=46), IIb (n=43), and IV (n=47). RESULTS: The sialic acid concentrations (mean+/-SD) in plasma apoB-containing lipoproteins were 19.4+/-5.9, 24.3+/-4.7 (P<0.0001 versus normal), 23.0+/-4.7 (P<0.0001), 27.9+/-5.2 (P<0.0001), and 22.3+/-3.4 mg/L (P<0.002), for normal, all types of hyperlipidaemia, types IIa, IIb, and IV, respectively. The contents of sialic acid in apoB were 2.03+/-0.41%, 2.09+/-0.35% (no significance versus normal), 1.86+/-0.27% (P<0.0001), 1.97+/-0.26% (P<0.02), and 2.28+/-0.41% (P<0.002), for normal, all types of hyperlipidaemia, types IIa, IIb, and IV, respectively. CONCLUSION: The content of sialic acid in apoB decreased significantly in type IIa but increased in type IV hyperlipidaemia, which may reflect the presence of sialic acid in very low-density lipoprotein apolipoproteins other than apoB. This simple precipitation method will be useful to evaluate the sialic acid content in low-density lipoprotein in hyperlipidaemic subjects, especially of type IIa.

[Convenient assay for glycated apolipoprotein B using protease].

The aim of this study is to develop a convenient method for monitoring glycated apolipoprotein B levels. Serum sample was treated with dextran-magnesium and the resulting precipitates were subjected to glycated albumin assay. Dissolving the precipitates by Triton X-100 and digesting by proteinase K enable the establishment of stable and sensitive assay. Intra- and inter assay coefficients of variation were 1.5-3.5% and 1.6-3.3%, respectively. The serum glycated apolipoprotein B values by present method correlated well with those by enzyme-linked immunosorbent assay (r=0.979). The serum glycated apolipoprotein B values in healthy subjects was 4.14+/-0.51% (mean+/-SD) with no significant difference between men and women and with no age-dependent variation. Patients with type 2 diabetes mellitus had higher serum glycated apolipoprotein B levels than the healthy subjects. This assay should further be investigated to establish the validity of glycated apolipoprotein B measurement in clinical field.

The absence of evidence for major effects of the frequent SNP +299G>A in the resistin gene on susceptibility to insulin resistance syndrome associated with Japanese type 2 diabetes.

Resistin, specifically secreted from adipocytes, antagonizes insulin and represents a promising candidate gene for type 2 diabetes. We reported that a frequent single nucleotide polymorphism (SNP) +299G>A in this gene is not associated with type 2 diabetes. To determine whether this SNP affects insulin resistance syndrome associated with type 2 diabetes, we examined its effects on susceptibility to obesity, hyperlipidemia and hypertension in type 2 diabetic subjects and on susceptibility to type 2 diabetes by interaction with other frequent genes involved in lipid metabolism, namely, beta3-adrenergic receptor (b3AR) Trp64Arg, phosphodiesterase 3B (PDE3B) c.1389G>A or lysosomal acid lipase (LAL) Thr-6Pro. The 99 type 2 diabetic and 99 control subjects were typed by PCR direct sequencing or PCR-RFLP. No differences in frequencies of obesity, hyperlipidemia and hypertension were found between the type 2 diabetic subjects with G/G and those with G/A or A/A genotypes of the resistin SNP. When the combination of the resistin SNP with each of b3AR, PDE3B and LAL SNPs was assessed, no association with type 2 diabetes was evident. Therefore, the frequent SNP +299G>A in the resistin gene is unlikely to have major effects on susceptibility to insulin resistance syndrome associated with type 2 diabetes in Japanese subjects.